Aza-hydroxy-benzanthrone

ABSTRACT

There is disclosed a new product of the benzanthrone class, namely, 1-aza-2-hydroxy-benzanthrone, useful in the synthesis of vat and azoic dyes. Briefly, the new product is obtained by reacting 1,4-napthoquinone with methyl-3,5-hexadienoate, under heating, and then treating the resulting solid product with excess NH3 in anhydrous alcoholic solution, and finally recovering the 1-aza-2-hydroxy benzanthrone.

United States Patent [191 Boffa et al.

[ 1 Oct. 14, 1975 AZA-HYDROXY-BENZANTHRONE [75] Inventors: Gioacchino Boffa; Gian Paolo Chiusoli, both of Novara, Italy [73] Assignee: Montecatini Edison S.p.A., Milan,

Italy [22] Filed: Mar. 5, 1970 [21] Appl. No.: 16,989

[30] Foreign Application Priority Data 4/1970 Hegar 260/278 X 7/1972 Boffa et al. 260/278 OTHER PUBLICATIONS King et al., Jour. Chem. Soc. (London), I954, pp.

The Colour Index, p. 3488, No. 60000.

Primary ExaminerDonald G. Daus ABSTRACT There is disclosed a new product of the benzanthrone class, namely, l-aza-2-hydroxy-benzanthrone, useful in the synthesis of vat and azoic dyes. Briefly, the new product is obtained by reacting 1,4-napthoquinone with methyl-3,5-hcxadienoate, under heating, and then treating theresulting solid product with excess NH in anhydrous alcoholic solution, and finally recovering the l-aza-2-hydroxy benzanthrone.

4 Claims, No Drawings 1 AZA-HYDROXY-BENZANTHRONE It is yellow in color, melts at 249C with decomposition, and crystallizes from n-butanol.

The invention also provides a two-step method for the preparation of the new product.

In the first step, l,4-naphthoquinone and methyl-3,5- hexadienoate, in about equimolar quantities, are heated together in an inert solvent, preferably in methanol or ethanol, at reflux temperature. The solid thus obtained (compound I) is filtered from the alcoholic solution and cooled at 0C to +C.

In the second step, compound I is treated with an excess of NH in anhydrous alcoholic solution, at a temperature of from 20C to +C, but preferably at room temperature. Thereupon, an alkaline hydroxide is added and air is passed through the mass, at atmospheric pressure and room temperature. The mixture is then diluted with water, filtered, and the red filtrate is acidified to precipitate the pure aza-hydroxybenzathrone, Compound II.

The two steps of the process can be represented by the following reactions:

CH -COOCH;

methyl-naphthoquinone-hexadienoate-1 tetrahydro-anthraquinone) -acetate. (adduct).

in the second step, at least 10 moles of ammonia and from 1 to 5 moles of alkalimetal hydroxide, preferably KOH, are used for each mole of starting naphthoquinone. The preferred alcohols are methanol and ethanol.

As already stated, the new product (compound II) is useful as an intermediate in the synthesis of vat and azoic dyestuffs.

The following examples are given to illustrate the invention and are not intended as limiting the invention.

EXAMPLE 1 This example is given to illustrate the preparation of compound I.

34.3 g of 1,4-naphthoquinone, 27.4 g of methyl-3,5- hexadienoate (the methyl ester of pentadiene carboxylic acid), and ml of 99% ethanol were boiled at reflux temperature under an N atmosphere for 6 hours. The solution thus obtained was cooled to 10C, and the solid which separated was filtered and washed on the filter with 38 ml of 99% ethanol, after which it was dried in the air. The product crystallized from methanol or ethanol in the form of white crystals having a melting point of 88C.

EXAMPLE 2 34.3 g of l,4-naphthoquinone, 27.4 g of methyl-3,5- hexadienoate, and 65 ml of methanol were boiled at reflux temperature for 6 hours, in a nitrogen atmosphere. The solution thus obtained was introduced into 940 ml of an anhydrous methanol solution saturated by NH and allowed to remain in said solution for 3 days under atmospheric pressure and at room temperature. Thereafter, a lively current of air was introduced into the reaction mixture for about one hour, to remove most of the NH Finally, 100 ml of methanol containing 10 g of KOH, and 250 ml of water were added. Air was bubbled through the mixture for another four hours, also at room temperature. The resulting red solution was d'iluted with 1300 ml of water, filtered, and acidified. The solid precipitate was filtered, washed with water until the acidity completely disappeared, and finally dried in vacuo on a water bath.

34.6 compound II were obtained. The IR, NMR and centesimal analyses showed that compound II was l-aza-2-hydroxy-benzanthrone.

The ready reactivity of compound II with ptoluenesulphonyl chloride in pyridine solution, and with diazomethane in dioxane solution, with the formal-aza'2-hydroxybenzanth rone 3 4 tion of quantitative yields of, respectively, the p-tola. l,4fnaphthoquinone and methyl-3,5-hexadienate uenesulphonic ester and the methyl ester, proved the are reacted, in about equimolar quantities, and the existence of the OH group in compound ll. adduct, methyl-naphthoquinone-hexadienoate thus What we claim is: formed, is separated in the form of white crystals; 1. l-Aza-2-hydroxy-benzathrone of the formula 5 and b. said adduct is treated with an excess of NH in an hydrous alcoholic solution, an alkaline hydroxide is added, air is passed through the mass, and the resulting solution is acidified to precipitate the l-aza-2-hydroxy-benzanthrone. 1

3. The process according to claim 2, further characterized in that step (a) thereof is carried out in a solvent selected from the group consisting of methanol and ethanol, at reflux temperature. i The process according to claim 2, characterized in that the treatment of the adduct with NH in step (b) 2. Process for preparing l-aza-2-hydroxy- -is carried out at room temperature. benzathrone characterized in that I 

1. 1-AZA-2HYDROXY-BENZATHRONE OF THE FORMULA
 2. Process for preparing 1-aza-2-hydroxy-benzathrone characterized in that a. 1,4-naphthoquinone and methyl-3,5-hexadienoate are reacted, in about equimolar quantities, and the adduct, methyl-naphthoquinone-hexadienoate thus formed, is separated in the form of white crystals; and b. said adduct is treated with an excess of NH3 in an hydrous alcoholic solution, an alkaline hydroxide is added, air is passed through the mass, and the resulting solution is acidified to precipitate the 1-aza-2-hydroxy-benzanthrone.
 3. The process according to claim 2, further characterized in that step (a) thereof is carried out in a solvent selected from the group consisting of methanol and ethanol, at reflux temperature.
 4. The process according to claim 2, characterized in that the treatment of the adduct with NH3 in step (b) is carried out at room temperature. 